The supplier who vanished taught me about financial due diligence. When I traced back the warning signs: they had quoted significantly below market, demanded a larger than standard deposit, and had been unusually eager to close the deal. In hindsight, they were likely in financial distress and using new orders to stay afloat. My standard process now includes a quick financial health check — business license age, registered capital, and credit references from other buyers.
A quality disaster early in my career taught me the difference between 'sample quality' and 'production quality.' Our samples were perfect — precise dimensions, flawless finish, beautiful packaging. The bulk shipment looked nothing like the sample. Colors were off, tolerances were sloppy, and 15% of units were damaged. I learned to always: (1) request samples from regular production, not specially prepared ones, (2) conduct pre-shipment inspection by a third party, (3) include clear quality specifications in the contract with measurable criteria.